Such constant study, however, swelled his passion which soon became exacting.

He asked himself whether he was really bound not to continue his researches, and remembered that his wife had refused his oath.

Though he had pledged his word to himself that he would never pursue the solution of the great Problem, might he not change that determination at a moment when he foresaw success?
He was now fifty-nine years old.

At that age a predominant idea contracts a certain peevish fixedness which is the first stage of monomania.
Circumstances conspired against his tottering loyalty.

The peace which Europe now enjoyed encouraged the circulation of discoveries and scientific ideas acquired during the war by the learned of various countries, who for nearly twenty years had been unable to hold communication.